1. Field of the Invention
The present invention relates to a multi type air-conditioner and a refrigerant control method thereof, and particularly, to a multi type air-conditioner and a control method thereof capable of improving cooling efficiency by preventing a liquid refrigerant from being accumulated in a high pressure pipe.
2. Description of the Conventional Art
In general, a multi type air-conditioner is provided with several indoor units, and accordingly some indoor units thereof perform a heating and the other indoor units thereof perform a cooling.
FIG. 1 shows a construction of a multi type air-conditioner according to the conventional art.
A multi type air-conditioner according to the conventional art includes: an outdoor unit 102 heat-exchanged with outdoor air; a plurality of indoor units 104 heat-exchanged with indoor air, for performing cooling and heating operations; and a distributor 106 provided between the outdoor unit 102 and the indoor units 104, for appropriately distributing a refrigerant of the outdoor unit 102 to the indoor units 104.
The outdoor unit 102 includes: a plurality of outdoor heat exchangers 108 heat-exchanged with outdoor air; a four-way valve 110 for switching a flow of a refrigerant in a forward direction or a reverse direction; an outdoor expansion valve 122 arranged in a refrigerant pipe 120 which is connected between the outdoor heat exchangers 108 and the indoor units 104, for changing the refrigerant into a state of low temperature and low pressure; a compressor 130 for compressing the refrigerant into a state of high temperature and high pressure; and an accumulator 132 connected to a suction side of the compressor 130, for dividing the refrigerant into gas and liquid and then supplying the refrigerant in a gaseous state to the compressor 130.
A blowing fan 134 for blowing outdoor air for heat-exchanging toward the outdoor heat exchangers 108 is installed at one side of the outdoor heat exchangers 108, and a bypass passage 126 having a check valve therein is installed at the refrigerant pipe 120 at which the outdoor expansion valve 122 is installed.
The indoor units 104 respectively includes an indoor heat exchanger 112 heat-exchanged with indoor air, and an indoor expansion valve 114 installed at one side of the indoor heat exchanger 112.
The distributor 106 includes: a high pressure pipe 140 connected to a discharge side of the compressor 130; first distributing pipes 144 diverged from the high pressure pipe 140 to each indoor unit 104; a low pressure pipe 142 connected to a suction side of the compressor 130; second distributing pipes 146 diverged from the low pressure pipe 142 to each indoor unit 104; first valves 150 installed at each of the first distributing pipes 144, for opening and closing the first distributing pipes 144; and second valves 152 installed at each of the second distributing pipes 146, for opening and closing the second distributing pipes 146.
Third distributing pipes 148 are diverged from the refrigerant pipe 120 which is connected to each of the outdoor heat exchangers 108, and thus connected to each of the indoor heat exchangers 112.
An operation of the air-conditioner according to the conventional art having such construction will now be explained. As shown in FIG. 1, if some of the indoor units 104 perform a cooling, and the other indoor units thereof perform a heating, the first valves 150 connected to the indoor heat exchangers 112 in a cooling operation mode are turned off, and the second valves 152 are turned on. Thereafter, the first valves 150 connected to the indoor heat exchangers 112 in a heating operation mode are turned on, and the second valves 152 are turned off.
In such a state, when the compressor 130 is driven, parts of the refrigerant compressed in the compressor 130 are condensed by passing through the outdoor heat exchangers 108 and then flow along the refrigerant pipe 120. Afterwards, the parts of the refrigerant are expanded with a reduced pressure by passing through the indoor expansion valves 114, and suck latent heat from the indoor heat exchangers 112, thereby performing a cooling operation. The parts of the refrigerant having passed through the indoor heat exchangers 112 flow into the compressor 130 through the second distributing pipes 146 and the low pressure pipe 142 because the second valves 152 are turned on and thus the second distributing pipes 146 are in an opened state.
The parts of the refrigerant compressed in the compressor 130 flow into each of the first distributing pipes 144 through the high pressure pipe 140. Accordingly, the first valves 150 are turned on so that the refrigerant is supplied to the indoor heat exchangers 112 through the opened first distributing pipes 144, thereby discharging heat and thus performing a heating operation. The refrigerant having passed through the indoor heat exchangers 112 joins the refrigerant flowing in the refrigerant pipe 120.
On the contrary, when all of the indoor units 104 perform the cooling operation, as shown in FIG. 2, the first valves 150 are turned off, and the second valves 152 are turned on. When the compressor 130 is driven in this state, the refrigerant compressed in the compressor 130 is condensed by passing through the outdoor heat exchangers 108, and then supplied to each indoor unit 104 through the refrigerant pipe 120 and each of the third distributing pipes 148. The refrigerant supplied to each indoor unit 104 is expanded with a reduced pressure by passing through the indoor expansion valve 114, so as to be supplied to the indoor heat exchangers 112. The refrigerant is heat-exchanged with indoor air while passing through the indoor heat exchanger 112, thereby performing the cooling operation. The refrigerant having passed through the indoor heat exchanger 112 flows into the compressor 130 through the opened second distributing pipes 146 and the low pressure pipe 142 as the second valves 152 are turned on.
However, in the air-conditioner according to the conventional art having such construction, when all of the indoor units 104 perform the cooling operation, because the first valve 150 is turned off and thus the high pressure pipe 140 is closed, parts of the refrigerant of high temperature and high pressure which has been compressed in the compressor 130 fill the inside of the high pressure pipe 140. Accordingly, the refrigerant is condensed in the high pressure pipe 140, and thereby a liquid refrigerant is accumulated in the high pressure pipe 140, which causes a lack of the refrigerant which should be circulated. As a result, the cooling capability is degraded.
In particular, if the high pressure pipe 140 is lengthened because of the distance between the indoor unit 104 and the distributor 106, a considerable amount of liquid refrigerant is accumulated in the high pressure pipe 140 and accordingly the refrigerant which should be circulated is insufficient, which results in damages by a fire on the compressor due to a lack of oil.